Bug with Window and nested layout

```rust
Window::new("test").show(ctx, |ui| {
ui.with_layout(Layout::bottom_up(Align::LEFT), |ui| {
ui.with_layout(Layout::right_to_left(), |ui| {
ui.label("footer");
});

ui.label("content");
});
});
```
This code makes the window expand in height at each redraw. Also the footer gets expanded so much that the content is pushed into the window header.